Blueberries and strawberries were part of this analysis simply because they are the most-eaten berries in the United States. Thus, it's possible that other foods could produce the same results, researchers said.

Scientists from the Harvard School of Public Health in the United States and the University of East Anglia, United Kingdom conducted a prospective study among 93,600 women ages 25 to 42 who were registered with the Nurses' Health Study II.

The women completed questionnaires about their diet every four years for 18 years.

During the study, 405 heart attacks occurred. Women who ate the most blueberries and strawberries had a 32-percent reduction in their risk of heart attack compared to women who ate the berries once a month or less - even in women who otherwise ate a diet rich in other fruits and vegetables.

"We have shown that even at an early age, eating more of these fruits may reduce risk of a heart attack later in life," Aedin Cassidy, lead author of the study at Norwich Medical School of the University of East Anglia in Norwich, United Kingdom, said.

The findings were independent of other risk factors, such as age, high blood pressure, family history of heart attack, body mass, exercise, smoking, caffeine or alcohol intake.

The study has been published in Circulation: Journal of the American Heart Association.